You’ve likely heard of Pangaea (not the one that sounds similar from Avatar), but you may not realize that it wasn’t the first supercontinent; several have been identified from the rock record. About a billion years ago, a supercontinent named Rodinia formed from the collision of a number of cratons which comprise parts of today’s continents. Evidence of the collisions that built Rodinia remains in a geological remnant called the Grenville mountain range.
Collisions of continents compress the crust between them, driving up a range of mountain peaks. We see a process like this going on today in the Himalayas, where the Indian plate is pushing northward into the Eurasian plate. With time, however, erosion will level out these mountains.
The Appalachian mountain range no longer reaches the impressive heights it once did because it has been eroding for over 400 million years. Deep in the roots of the Appalachians, though, we can see evidence of an even older mountain range that has long-since eroded from sight. The remnants of the Grenville range extend along the East Coast of the United States, but also continuing north into Canada as well as south through Texas and into Mexico.Â
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